Hello. Thanks. This is a valid point about stone identification. At Arrowe Park one stone still there is clearly ancient and still standing and on the old OS maps. This is used in my analysis. A second was not on the maps but clearly a dressed modern (i.e. Victorian) stone post complete with iron fittings. Four very similar dressed posts line an old forest pathway to the golf course nearby. They too were omitted from the OS maps. A third roughly shaped old stone (by its condition) but with a piece of iron attached was also recorded on the OS maps and I used it in my analysis.

I agree that given the uncertainties about the age of now missing stones other evidence is needed. That comes from pattern analysis and statistics. At Arrowe Park 8 stones forming two concentric circles is extremely improbable. At Overchurch 7 stones forming a good circle (allowing as you said for errors
-6
of +/- several feet) by chance has a probability of ~ 4 x 10.

Prof. Dave Gregg